Tamper evident bands are used to seal and/or package containers and are extensively used in a wide variety of containment applications. They generally consist of a relatively thin plastic circular band. In some applications, they are placed circumferentially around the interface of a container and its associated lid. When the lid is moved, the band is disrupted, signaling that the container has been tampered with. Most consumer product packages that utilize screw-on or snap-on lids also use tamper evident bands to ensure that consumers receive unopened merchandise. Nearly all drug packages involving screw-on lids use tamper evident bands to ensure that the drugs have not been adulterated after packaging. In other applications, the band may be placed around two or more containers so that they are held together and unitarily packaged. Tamper evident bands are often used to effectively and efficiently package multiple articles even where tampering is not a concern.
Application of tamper evident bands to a container or containers can be accomplished as follows. A tamper evident band supply strip in the form of a rolled, flattened tube is fed to a cutter. The cutter cuts the strip into individual flattened bands. The band is then engaged and held at one point by a point source grasping apparatus, usually a suction pod, such that the band droops downwardly expanding to a generally circular shape. The container or containers are conveyed past the drooping band, and as a result of its placement, they engage and strip the same from the suction pod. Once the band has been stripped, the band and container pass beneath a slanted plate guide which forces the band down onto the container so that it properly circumscribes the container. The container or containers with the band are subsequently heat treated to shrink and secure the band.
While the basic steps of the method just described are theoretically cost effective and efficient in applying tamper evident bands, these steps have several significant drawbacks in practice.
One problem is the inability to adequately control the position of the band. The size of the band and the size of the container are usually very close and, in order for the application to be effective, they must be properly held and oriented relative to each other. The band itself is light-weight, flexible and, because it usually originates from a flattened and rolled state, tends to assume an irregular shape. Very often a point source grasping apparatus such as a suction pod or cup allows the band to droop in a position that is out of proper alignment with the oncoming container. Moreover, static electricity inherent in the band inhibits the band from expanding properly. If the band and container are not properly oriented, the application fails. This problem is even more pronounced when the container and band are larger and therefore harder to control. There exists a need for an improved cost-effective and efficient means for positively orienting the band with respect to the path of the container.
Another problem inherent in the use of a point source for engaging the band is the tendency for the suction pod to inadequately grasp the band. The band must somehow be pushed up against the suction pod to aid in the grasping process. The nature of the plastic band further compounds the problem. The surface of the band does not always conform to the surface of the pod. This can present a problem because the band must be positively attached to the vacuum pod. Because the band is formed of thin plastic and originates as a flattened roll, it tends to have a relatively large amount of static electricity. In particular, the static electricity tends to cause segments of the band to "cling" together and resist opening. Therefore, there exists a need for an improved grasping system which positively directs the band against the suction pod and which neutralizes the static electricity associated with the band such that the band will open and droop relatively long.
As previously mentioned, tamper evident band application machines generally utilize a plate guide to ultimately position the band onto the container. The plate guide is usually stationary. Some attempts have been made to positively press down the band with the plate guide, being moved up and down by a spring loaded plate. Because the ultimate position of the band on the container is both aesthetically and functionally important, there exists a need for an improved plate guide which will efficiently and cost-effectively position the band on the container.